Abstract
Abstract: :
Purpose: To demonstrate the enhancing characteristics of porous polyethylene (MedPor) orbital implants with gadolinium-enhanced magnetic resonance imaging (MRI) and to emphasize the importance of distinguishing this predictable enhancement from enhancement secondary to orbital recurrence of retinoblastoma. Methods: Serial T1-weighed gadolinium-enhanced intracranial and orbital MRIs were preformed on patients with risk for trilateral retinoblastoma or risk for recurrent orbital disease who had undergone enucleation with placement of a MedPor orbital implant. Retrospective evaluation of the MRI enhancement patterns in recurrent retinoblastoma and in MedPor orbital implants was performed. Histopathologic correlation of fibrovascular ingrowth into a MedPor implant was achieved by evaluating an extruded implant. Results: Recurrent orbital retinoblastoma appears as a bulky, soft tissue mass that enhances on gadolinium-enhanced MRI. MedPor orbital implants also enhance with gadolinium-enhancement on MRI, but this pattern is confined within the implant sphere and progresses from the surface of the implant toward the center. Histopathology correlates fibrovascular ingrowth into the MedPor implant. Conclusions: Serial MRI is being used to evaluate high-risk retinoblastoma patients for trilateral disease and orbital recurrence. MedPor orbital implants are cost-effective and widely available. Normal enhancement patterns with MedPor orbital implants must be distinguished from enhancement secondary to recurrent retinoblastoma. Fibrovascular ingrowth and integration of the orbital implant likely correlates with enhancement on MRI.
Keywords: retinoblastoma • imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • orbit